Home
Class 11
MATHS
cos(36^@-A)cos(36^@+A)+cos(54^@+A)cos(54...

`cos(36^@-A)cos(36^@+A)+cos(54^@+A)cos(54^@-A)`=`cos2A`

Text Solution

AI Generated Solution

Promotional Banner

Topper's Solved these Questions

  • TRIGONOMETRIC RATIOS OF COMPOUND ANGLES

    RD SHARMA ENGLISH|Exercise All Questions|149 Videos

Similar Questions

Explore conceptually related problems

Prove that: i) cos10^(@)cos30^(@)cos50^(@)cos70^(@)=3/16 ii) cos20^(@)cos40^(@)cos60^(@)cos80^(@)=1/16 iii) 4cos12^(@)cos48^(@)cos72^(@)=cos36^(@) iv) cos40^(@) cos80^(@)cos160^(@)=-1/8

Prove that: cos(45^(@)+A) cos(45^(@)-A)=1/2 cos2A

The value of cos(-89^(@))+cos(-87^(@))+cos(-85^(@))+…+cos(85^(@))+cos(87^(@))+cos(89^(@)) is equal to

cos 12 ^(@) cos 24 ^(@) cos 36 ^(@) cos 48^(@) cos 72^(@) cos 84^(@) = (1)/(2 ^(6))

The value of cos12^(@)cos24^(@)cos36^(@)cos48^(@)cos72^(@)cos84^(@), is

Find the value of ((cos1^(@)+sin1^(@))(cos2^(@)+sin2^(@))(cos3^(@)+sin3^(@))...(cos 45^@sin45^@))/( cos1^(@)cos2^(@)cos3^(@)...cos45^(@))

The value of cos^(2)10^(@)-cos10^(@)cos 50^(@)+cos^(2)50^(@) is k/2 . The value of k is ________.

Prove that: cos(A+B+C)+cos(A-B+C)+cos(A+B-C)+cos(-A+B+C)=4cos A\ cos B\ cos C

Prove that cos 36^(@) cos 72^(@) cos 108^(@) cos 144^(@)=1//16 .

Evaluate : cos^(2)76^(@) +cos^(2)16^(@) - cos76^(@).cos16^(@)

RD SHARMA ENGLISH-TRIGONOMETRIC RATIOS OF MULTIPLE AND SUBMULTIPLE ANGLES-All Questions
  1. Prove that: cos(pi/7)cos(2pi/7)cos(4pi/7)=-1/8,

    Text Solution

    |

  2. If sin x+cos x=a , find the value of sin^6x+cos^6xdot

    Text Solution

    |

  3. If sin x+cos x=a , find the maximum and minimum value of a

    Text Solution

    |

  4. 8*sin(x/8)*cos(x/2)*cos(x/4)*cos(x/8)=

    Text Solution

    |

  5. Show that cos(pi/65)cos((2pi)/65)cos((4pi)/65)cos((8pi)/65)cos((16pi)/...

    Text Solution

    |

  6. For all real values of x ,cotx-2cot2x is equal to a.tan2x b. t a n x c...

    Text Solution

    |

  7. The value of 2tanpi/(10)+3secpi/(10)-\ 4cospi/(10) is 0 b. 1 c. sqrt(5...

    Text Solution

    |

  8. If in a Delta ABC, tanA+tanB+tanC=6 then cotA cotB cot C= a.6, b. 1, c...

    Text Solution

    |

  9. If sin alpha+sin beta=a\ a n d\ cosalpha-cosbeta=b , then tan(alpha-be...

    Text Solution

    |

  10. The value of t a nthetasin(pi/2+theta)cos(pi/2-theta) is -1 b. 1 c. ...

    Text Solution

    |

  11. Prove that: sin^2pi/(18)+sin^2pi/9+sin^2(7pi)/(18)+sin^2(4pi)/9=2

    Text Solution

    |

  12. If A=2sin^2theta-cos2theta, t h e n A lies in the interval (a)[-1,3] ...

    Text Solution

    |

  13. The value of cos^2(pi/6+theta)-sin ^2\ (pi/6-theta) is (a)dot 1/2cos\...

    Text Solution

    |

  14. The value of (cos3theta)/(2cos2theta-1) is equal to (a) costheta (b) ...

    Text Solution

    |

  15. The value of (2(sin2theta+2cos^2theta-1))/(costheta-sintheta-cos3theta...

    Text Solution

    |

  16. 2(1-2sin^2 7theta)sin3theta is equal to a.\ sin 17theta-sin 11theta b....

    Text Solution

    |

  17. cos(36^@-A)cos(36^@+A)+cos(54^@+A)cos(54^@-A)=cos2A

    Text Solution

    |

  18. Prove that: t a nthetatan(60^0-theta)tan(60^0+theta)=tan3thetadot

    Text Solution

    |

  19. tantheta+tan(6 0^0+theta)+tan(12 0^0+theta)=3tan3theta

    Text Solution

    |

  20. sin(5theta)/sintheta is equal to a.16cos^4theta-12cos^2theta+1, b.16co...

    Text Solution

    |